ARRANGEMENT FOR FEEDING OUT FIBRE BUNDLES WITH RANDOM FIBRE DIRECTION

Abstract: An arrangement for repeatedly feeding out fibre bundles with random fibre direction from a magazine roll of fibre thread (10), for example in the production of flock preforms for products made of thermosetting resin. The arrangement comprises feed devices (11, 12, 16, 17) for feeding the fibre threads from the magazine roll and cutting devices (18, 19) for cutting the fibres into desired lengths. The feed devices comprise at least a first and a second pair of driven feed rollers (11, 12 and 18, 19) placed in sequence, which feed rollers form nips for the fibre threads (10). A pneumatically driven fibre-ejecting device (20) placed downstream of the cutting device (18, 19). The first pair of feed rollers (11, 12) is driven at slightly lower feeding speed than the second pair of feed rollers (18, 19). The fibre ejection devices include an oblong tube sleeve (26) with air flow channels (22-25) for directed turbulent air flow.

Description: P14841.PC TITLE Arrangement for feeding out fibre bundles with random fibre direction. TECHNICAL FIELD The present invention concerns an arrangement for repeatedly feeding out fibre bundles with random fibre direction from a magazine roll of fibre thread, for example in the production of flock preforms for products made of thermosetting resin, which arrangement comprises feed devices for feeding the fibre threads from the magazine roll and cutting devices for cutting the fibres into desired lengths, said feed devices comprising at least a first and a second pair of driven feed rollers placed in sequence, which feed rollers form nips for the fibre threads, and a pneumatically driven fibre-ejecting device placed downstream of the cutting device. BACKGROUND OF THE INVENTION The production of fibre-reinforced thermosetting resin products is difficult to automatize since the quality of the product depends to a great extent on how the fibres are oriented with respect to how the product will be subjected to loading. Modern quality standards usually require a product to have an exact quantity of fibres that are oriented to obtain maximum strength without the fibres penetrating the product's outer plastic layer. It is customary to use very thin fibres, known as surfacing mat fibres, in the outer fibre layer. This prevents the more robust fibres of normal thickness from penetrating the outer plastic layer of the thermosetting resin product. Such penetration would otherwise lead to the product having to undergo a costly manual after-treatment. TECHNICAL PROBLEM The aim of the present invention is to produce an arrangement for feeding out thin fibre bundles, which bundles can be used as surfacing mat layers in the manufacture of thermosetting products, and which arrangement makes it possible to automatize the addition of reinforcing fibres to a product, for example by using an industrial robot, so that flock preforms can be repeatably produced. THE SOLUTION For this purpose the invention is characterized in that the first pair of feed rollers is driven at slightly lower feeding speed than the second pair of feed rollers, and that the fibre ejection devices include an oblong tube sleeve with air flow channels for directed turbulent air flow. DESCRIPTION OF THE DRAWING The invention will be described below with reference to a given embodiment, which is shown in the attached drawing. The drawing is a schematic representation showing a side view of the arrangement according to the invention. DESCRIPTION OF THE GIVEN EMBODIMENT In the arrangement shown in the drawing a continuous multiple- and fine-threaded glass fibre 10 is fed from right to left into the nip between two rollers 11, 12 from a magazine roll (not shown). The roller 11 is displaceably journalled and is pressed towards the other roller 12 by the action of a compression spring 13. The roller 12 is driven via a toothed belt 14, which runs round the two toothed gears 15 and 16. The gear wheel 15 is connected to the roller 12, while the other gear wheel 16 connected to a knife roller 17, which is provided with four knife blades 18 directed along its periphery. The blades are spaced evenly along the circumference of the roller 17. rubber cylinder 19 is in contact with the roller 17 and acts as a reverse roller to roller 17 and against the knives 18. The roller 17 can be driven at variable speeds with a rotational speed V x by a driving motor (not shown). The speed adjustment can preferably be carried out with the help of pulse-counting devices. As the gear wheel 15 is somewhat larger than the gear wheel 16, it is driven at a slightly lower speed V 2 than the gear wheel 16. As a result of this difference in speed, a stretching of the individual fibres in the fibre bundle of the thread 10 is achieved, so that the bundle is flattened out transversely in the nip between the roller 17 and the cylinder 19. A fibre feeding head is placed downstream of the pair c with a central passage 21 for the severed fibre bundle. An annular slit 22 is arranged concentrically around the passage 21 and is connected via a channel 23 to an air pressure source. A number of secondary channels 24 are connected with the channel 23 and open out downstream of the slit 22. The compressed air that is forced into the fibre feeding head 20 via the channel 23, the slit 22 and the secondary channels 24 brings ambient air via the passage 21. Moreover, additional air is ejected via a number of concentrically arranged air openings 25. As a result of the achieved blowing effect, the fibre bundles severed from the thread 10 will be subjected to a turbulent air flow causing them to be bent and scattered in all directions to form a "woolly tuft" when they come into contact with the inner wall of an oblong tube sleeve 26, which forms an extension of the fibre feeding head 20. The arrangement described above should preferably be mounted on a robot arm (not shown), which is freely moveable in space and is controlled by a programmable microprocessor. The invention is not limited to the embodiments described above. Further variations are conceivable within the scope of the following claims.

Claims: PATENT CLAIMS 1. An arrangement for repeatedly feeding out fibre bundles with random fibre direction from a magazine roll of fibre thread (10), for example in the production of flock preforms for products made of thermosetting resin, which arrangement comprises feed devices (11, 12, 16, 17) for feeding the fibre threads from the magazine roll and cutting devices (18, 19) for cutting the fibres into desired lengths, said feed devices comprising at least a first and a second pair of driven feed rollers (11, 12 and 18, 19) placed in sequence, which feed rollers form nips for the fibre threads (10), and a pneumatically driven fibre-ejecting device (20) placed downstream of the cutting device (18, 19), c h a r a c t e r i z e d in that the first pair of feed rollers (11, 12) is driven at slightly lower feeding speed than the second pair of feed rollers (18, 19), and that the fibre ejection devices include an oblong tube sleeve (26) with air flow channels (22-25) for directed turbulent air flow. 2. An arrangement according to claim 1, c h a r a c t e r i z e d in that the channels include an annular slit (22) concentrically surrounding a central passage (21 ) for the severed fibre bundle, a number of secondary channels (24), and air openings (25).

Inventors: SAND KJELL, SAND, KJELL
Applicants: APLICATOR SYSTEM AB, SAND KJELL, SAND, KJELL
Application year: 1994
Main classification: C03B37
IPC codes: B29C70, C03B37, D04H1